Tooth pins for artificial teeth



Feb. 22, 1938. F. MAULEN TOOTH PINS FOR ARTIFICIAL TEETH I m M M M 0" 9INVENTOR BY I . v I I TORNEY Patented Feb. 22, 1938 UNiTED STATES'roo'rn rms roa TEETH Frederick Maulen, East Orange. N. 1., assignor toBaker & Company, Inc., a corporation of New I Jersey ApplicationSeptember 28, 1935, Serial ire/42,639

In Canada October 5, 1934 l Claims.

The invention relates particularly to tooth pins for artificial teethandmethods of making them, i.-e., pins that are used for attachingartificial teeth to vulcanite backings or other supports, al-

though the invention is susceptible for use in and for making otherdental accessories. More spe-.

cifically the invention is directed to the manufacture of tooth pins ofthe type including cores of base metal, such as nickel or nickel alloys,having to a plurality of superposed layers or coatings of many years.These pins have been made by $111)! ping a tube of gold over a rod ofbase metal and then rolling and drawing the composite rod into finewire. However, it has not been possible to prevent scratching, tearingor cracking of the coating layer by hard particles in the drawing stoneor in drawing the coating eccentric to the core, during this operation,which results in a weakening of the protective coating or exposure ofthe base metal to corrosion. Moreover, the use of single coatings ofgold or gold-platinum alloys, has been restricted by the high cost,sincethick layers (25% by weight of the core) are necessary to providethe desired protection againstcorrosion of the core either by thesoldering operation or mouth fluids.

These disadvantages led to the production of a pin having a base metalcore and two or more superposed thin coating layers of different metalsor alloys, the inner layer being of a metal of the platinum group, forexample platinum or palladium, or silver, or an alloy of two or more ofthese metals, or an alloy of one or more of said metals and gold, whilethe outer layer is formed of gold or gold alloy. The gold outer layertends to fill in any cracks in the inner coating, while the inner layerserves as a buffer between the core and the outer layer.

Furthermore, by using for the inner or buffer coat a metal of lowerspecific gravity and less expensive than gold, for example, palladium, athicker inner coating or butter layer can be used with a relatively thinouter layer of *gbld, so that the core with the inner layer can b moreeasily ture thereof according to the preferred form of drawn or workedwith less danger of tearing or cracking, and yet the pin will be lessexpensive and have corrosion resisting qualities at least equal instrength and durability to known single coated pirTs. 5 Where certainmetals, for example, palladium and silver, are used for the intermediateor buffer layer, difiusion of the outer layer into it may take placeparticularly under relatively high temperatures, for exampleduring-soldering operations on the pin. This results in weakening of theprotective coatings and renders the pin less resistant to corrosion inaddition the desirable gold color may be lost when gold is used for theouter coating. 15

Therefore prime objects of my invention are to provide a-novel andimproved method of making a tooth pin or dental accessory of the generalcharacter described whereby diifusion of the outer layer into'the inneror bufier .layers shall be prevented or reduced; and to provide toothpins or other dental accessories which have a base metal core coveredwith a plurality of diflerent corrosion resistant, preferably precious,metals or alloys, and an intermediate diffusion preventing I layer ofmetal.

7 Other objects are to provide a tooth pin or dental accessory of thegeneral character described which shall have a layer of corrosionresistant, preferably precious, metal, for example 30 rhodium orplatinum, over the first coating or inner or buffer layer to preventdiffusion of the outer layer or layers into the initial or buifer layer;and to obtain other results and advantages as will be brcught out by thefollowing description. 1

For the purpose of illustrating the principles of the invention, theaccompanying drawing shows a tooth pin and the steps in the manufac- 40the invention.

Referring to the drawing in which corresponding and like parts aredesignated by the same reference characters throughout the severalviews, v Figure 1 is a fragmentary side elevation, on a greatly enlargedscale, of a base metal rod having a layer or plating of precious metalthereon.

Figure 2 is a similar 'view, showing the rod after it has been rolledand drawn into wire,

Figure 3 is a view, partially in elevation and partially in longitudinalvertical section, of a tooth pin formed from the wire shown in Figure 2.

*igvre 4 is a similar view showing the pin after Figure 5 is a likeview, showing the completed pin after the outer layer of protectingmetal has been applied thereto; and

Figures 6, '7, and 8 are sectional views illustrating the steps 'inanother method of applying the inner protective layer to the base metalcore. Specifically describing the preferred manner of carrying out theinvention, a protective or buffer layer 2 of precious metal or aprecious metal alloy is first applied to a rod I of base metal, forexample nickel or a nickel alloy. This protective layer 2 may beappliedto the rod I in any suitable. manner, but preferably the layer 2consists of a tubular shell which is slipped over the core I and is thensecured on the. core under influence of heat and pressure in knownmanner. Instead of this method a sheet I of the protective metal may besoldered on a sheet 8 of base metal as shown in Figure 6, after whichthe composite sheet can be formed by dies into a tube as shown in Figure'7. Then a solid core 9 can be soldered into the tube as shown in Figure8, and the whole drawn into a wire of the desired diameter. Thecomposite rod is rolled and drawn into a wire of suitable diameteraccording to known methods.

Preferably this inner layer 2 is composed of a metal of the platinumgroup or an alloy thereof, for example platinum, palladium, orplatinumgold alloy, palladium-silver alloy, palladium-gold alloy orpalladium-gold-silver, or silver alone may be used where solderingtemperatures are low.

The wire shown in Figure 2 is then cut into pieces of the desired lengthto form tooth pins or other dental accessories, and these pieces may beused as tooth 'pins with or without heads. Preferably each piece isprovided with a head 3 by upsetting the end of the piece as shown inFigure 3. During this operation, the protecting layer 2 at the head ofthe pin is attenuated and due to the larger cross section area of thehead, the coating layer does not entirely cover the end of the head sothat a small area 4 of the base metal core is exposed; also the basemetal core at the other end of the pin where the piece of wire has beensevered is exposed as indicated mi, and the layer at the juncture of thehead with the shank is thinned at 50. Furthermore, the layer 2 may betorn, cracked, or scratched, or drawn eccentrically. The same resultsoccur in pins having two protective layers, and accordingly such pinsare inadequately protected against corrosion or oxidation of the core.

In accordance with the invention, after the pins have been formed asdescribed above, a thin or "flash" coating III of a corrosion resistantmetal is applied over the inner or buffer layer 2, particularly when thelatter is of a nature to permit diffusion thereinto of another layerunder heat, for example during soldering operations on the pin. Forexample, palladium or silver or alloys thereof when usedto providethebufier coating, may be covered with a diffusion preventing coating ofrhodium or platinum. Preferably the rhodium or platinum or other metalused for the diffusion preventing coating is electrodeposited on thepin, and preferably the pins are wholly submerged in an electroplatingsolution, the coating being electrodeposited on the pins while thelatter are being agitated. In this way the difl 'usion preventingcoating I0 is thus applied to the whole surface of the pin over theinner layer 2, and the portions 4, 5 and 50 of the core.

After the diffusion preventing layer III has been applied to the pins asdescribed above, another protecting layer 6 of precious metal is appliedto the pin, preferably by electrodeposition in substantially the samemanner in which the layer I0 is applied. This final or outer protectinglayer 6 is preferably of gold or a gold alloy, and due to the presenceof the diflusion preventing layer III, the tendency of the gold todifluse into the inner layer 2 is prevented or reduced. Byelectrodepositing the layer 6, as described, the layer obtained issmooth, of uniform thickness and of high quality. Also, any cracks,scratches or tears in the inner layer formed during the drawing orrolling operations are filled in and covered by the outer layer 6. Theouter layer covers all portions of the pin which are thereby effectuallyprotected against corrosion.

The diflusion preventing layer or coating of platinum or rhodium mayconsist of from onequarter to one-half of one percent by weight of thecore, although the thickness of layer may be widely varied as desired.With such a diffusion preventing coat less gold is required than withoutsuch coat to provide a given degree of corrosion resistance. Also, thethin diffusion preventing coat will so greatly reenforce or supplementcorrosion resistance of the silver, that silver may be more generally orwidely used in such tooth pins; and thereby due to relative low cost ofsilver the pins can be made at less cost.

The inner layer maybe thick to partially overcome the diificultiesencountered in working or drawing of the wire and the outer layer may berelatively thin, and yet provide adequate protection for the core atrelatively small cost; this is especially true when the inner layer isof metal less expensive and has a lower specific gravity than gold, suchas palladium, and the outer layer is of gold. This is important becauseit is diflicult to electrodeposit thick layers of metal while thinlayers can be easily electrodeposited; on the other hand, thin layerscan be drawn only with difiiculty and thick layers can be easily drawn.The use of a thin outer layer is further facilitat'ed by the diffusionpreventing layer III which insures that the outer layer shall notdifiuse into the inner layer. Accordingly, it is possible to use a thickinner layer 2 of, for example, palladium and a relatively thin outerlayer of for example gold, and provide a relatively inexpensive pin,although, of course, the outer layer may be made of any desiredthickness. As is known to those skilled in the art, the use of gold asan outer layer is highly desirable because, from long use thereof,dentists have come to believe that it is the best metal for dentalpurposes and it has an appearance which is pleasing and instantlysignifies to the observer that it is of precious metal.

While the thicknesses of the layers 2 and 6 may be widely varied to suitdifferent conditions, in the preferred tooth pins, especially wherepalladium is used as the inner layer, the layers each consist of abouteight per cent by weight of the core.

Obviously, the layers may be formed of different metals as desired, forexample, the inner layer might be of'gold and the outer layer ofplatinum, and other metals than those-enumerated suitable for thepurpose may be utilized.

While for most purposes it is generally will- .cient for a tooth pin orthe like to be provided,

in accordance with this invention, with only two coatings of differentcorrosion resistant precious metals, it will be apparent from theforegoing that more than two coatings may be provided, if desired.

Having thus described my invention, what I claim is: v

1. Dental accessories formed of a base metal covered with a plurality oflayers of diiferent corrosion resistant precious metals one of which isof a nature to permit diffusion thereinto of another under solderingtemperatures, and an intermediate thin coatingof a diffusion preventingof rhodium and the first layer comprises palladium.

5. Dental accessories as set forth in claim 1 wherein the diffusionpreventing layer is formed of platinum and the first layer comprisespalladium.

6. Dental accessories as set forth in claim 1 wherein the diffusionpreventing layer is formed of rhodium and the first layer comprisespalladium and the outer layer consists of gold.

'7. Dental accessories as set forth in claim 1 wherein the diffusionpreventing layer is formed of platinum and the first layer comprisespalladium and the outer layer consists of gold.

8. Dental accessories as set forth in claim 1 wherein the diffusionpreventing layer is formed of rhodium and the first layer comprisespalladium or an alloy thereof, and the outer layer is gold.

9. Dental accessories as set forth in claim 1 wherein the diffusionpreventing layer is formed of rhodium in an amount approximately fromone-quarter to one-half of one percent by weight of the core, andwherein the first layer and outer layer comprise palladium or an alloythereof and gold respectively, each in an amount approximately eight percent by weight of the core.

10. Dental accessories formed of a base metal covered with a pluralityof layers-of different corrosion resistant precious metals one of whichis of a nature to permit diffusion thereinto of another under solderingtemperatures, and an intermediate thin coating of one or more metals ofthe group consisting of platinum and rhodium between said layers toprevent diffusion of the second-mentioned layer into the first-mentionedlayer.

11. A tooth pin or other metallic dental 8.0-, cessory having a basemetal core, an innerlayer of silver or an alloy thereof, an outerelectrodeposited layer of precious metal and an electrodeposited coatingof platinum between said outer layer and said inner layer to preventdiffusion of the outer layer into said inner layer.

12. A tooth pin or other metallic dental accessory having a base metalcore and inner and outer electro-deposited layers of corrosion resistantprecious metals, the inner of which is of a nature to permit diffusionthereinto of the outer layer under soldering temperatures, and adiffusion preventing layer of a metal between said inner and outerlayers to preventdiflusion of the outer layer into said inner layer.

13. A tooth pin or other metallic dental accessory having a base metalcore, an inner layer of palladium or an alloy thereof, an outerelectrodeposited layer of precious metal and an electrodeposited coatingof rhodium between said outer layer and said inner layer to preventdiffusion of the outer layer into said inner layer.

14. A tooth pin or other metallic dental accessory having a base metalcore, an inner layer of palladium or an alloy thereof, an outerelectrodeposited layer of precious metal and an electrodeposited coatingof platinum between said outer layer and'said inner layer to preventdiffusion of the outer layer into said inner layer.

15. A tooth pin or other metallic-dental accessory having a base metalcore, an inner layer of silver or an alloy thereof, an outerelectrodeposited layer of precious metal and an electrodeposited coatingof rhodium between said outer layer and said inner layer to preventdiffusion of the outer layer into said inner layer.

16. A tooth pin or other metallic dental accessory having a base metalcore, an inner layer of palladium or an al oy thereof, an outer electrodeposited layer of gold, and an electrodeposited flash coating ofrhodium between said outer layer and said inner layer to preventdiffusion of the outer'layer into said inner layer.

1'7. A tooth pin or other metallic dental accessory having a'base metalcore, an inner layer of palladium or an alloy thereof, an outerelectrodeposited layer of gold, and an electrodeposited flash coating ofplatinum between said outer layer and said inner layer to preventdifluslon of the outer layer into said inner layer.

FREDERICK MAULEN.

